Lifting-jack



C. F. L. KING.

LIFTING JACK.

APPLICATION FILED IIILY 7. |919.

v1 60,762. Patented Nov. 30, 1920.

3 SHEETS-SHEET l.

C. F. L. KING.

LIFTING JACK.

APPLICATION FILED IuLY I. ma.

3 SHEETS-SHEET 2.

Patented Nov. 30, 1920.

3 SHEETS-SHEET 3- Patented Nov. 30., 1920.

avi -..113141:

C. F. L. KING.

LIFTING JACK.

APPLICATION FILED JULY 7, 1919.

Fly. 6.

new/ogg@ @ii/@ses f' CHARLES F. L. KING, (1F-BIRMINGHAM, ENGLAND.

LIFTING-JACK.

vSpecication of Letters Patent. Patented NOV, 30, 1920.

Application filed July 7, 1919. serial No. 309,005. Y

To all whom 'it mag/concern. Y

Be 1t known that I, CHARLESFREDERICK LAWRENCE KING, a subject of the King of Great Britain, residing at Birmingham,

England, have invented certain new and usei ful Improvements ill Lifting-Jacks, of which the following is a specification.

This invention relates to lifting jacks of the pawl-and-ratchet type and has for its object" to provide improved and Simplified nleans for lowering the load.

The invention has more particular reference to jacks in which, for the purpose of lowering, the pawls are alternately thrown out of engagement by trip members carried by a rocker or movable member which is adapted to be secured in an inoperative position, when the trip members have no effect on the pawls, for the purpose of lifting.

According tothe present invention the rocker-is adapted to be lockedl or held in an operative position for lowering, as well as in an inoperative position for lifting, and carries trip members in the form of springactuated levers or angularly moving parts.

The trip members, when in operative position, are arranged so that as such pawl desccnds the corresponding trip member moves it out of engagement while the other pawl moves into engagement but said disengaged pawl engages with another tooth when again' lifted. In thev case of a single-acting jack having one lifting pawl coperatng with a retaining pawl, the trip member for throwing out the latter is arranged to be o er-l ated by the raising of the lifting paw as the later moves into engagement. The pawls are arranged to be takenV into engagement by springs which are weaker than, and

adapted to be overpowered by thetripy springs.

Figure 1 of the accompanying drawings is a side elevation of a double-acting jack constructed in accordance with ythe present invention, the front cover-plate being removed, and the trip levers being in their inoperative position to allow the jack being used for lifting. I

Fig. 2 isa cross-section on line Fig. 1. Fig. 3 is a vertical section showing the lifting pawls in engagement with the rack. Fig. 4 shows the rocker plate held in the position in Vwhich the trip levers are operative upon the lifting pawls, so as to allow of the load being lowered. This View shows the handle in the raised position, and the load supported by the upper pawl.

Fig.` 5 is a similar view, but shows the handle in the lowered position, and the load supported by the bottom pawl.

Fig. 6 represents a side elevation of a single-acting Ijack constructed in accordance with this illvention.

Fig. 7 shows a further modication.

Referring to the double-acting jack shown in Figs. 1 to 5, operating lever 1 is fulcrumed at 2 within a casing 3 carried by the fixed frame 4 of the jack, and has two pawls 5, 6, pivoted to it upon opposite sides of the fulcrum, so that as the lever is oscillatcd in a vertical plane the one pawl moves upward and the other downward. The said pawls engage with a ratchet toothed rack upon the lifting pillar 8 of the jack, and are kept in engagement therewith by means of light springs y9, 10, (see Fig. 3) which cause the pawls, as they descend, to wipe over the teeth in order to engage a lower tooth and support the load as each stroke is completed. Thus, the load is raised by the outer pawl 5 when the lever is lifted and by the inner pawl 6 when the lever is de pressed.

To enable the load to be lowered, each pawl carries a laterally projecting pin 11, 12, and beneath these pins are trip levers 13, 14, both levers being pivoted, at one end, to a rocker plate or arm 15 pivotally mounted at its lower end, as at 16. The trip 1ejoted detent or catch comprising a lever 21 extending through a slot in the side v,of the casing and having a nose 22 which, in the lifting position of the trip levers, engages beneath a tooth or projection 23 on the rocker 15, as shown in Fig. 1. To place the tripv levers in a position to permit of lowering, the outer end of the detent 21 is pressed downward, causing the inner end to move upward and swing over the rocker into the position shown in Figs.l 4 and 5, said rocker being retained in this position by the nose 22 of the detent engaging behind the shoulder of the tooth 23, as shown.

In .this position the pawls are raised into theposition shown, with their upwardly i1l clined nose ends 'immediately beneath the pins 11, 12 oni the pawls. When the operating lever 1 is raised as in Fig. 4, the inner pawl 6 is in the lowered position and its pin 12 is engaged and acted upon by the lever 14, so that the said pawl is held out of engagement with the rack, while the load is supported by the outer or upper pantie..

On depressing the operating lever, the load is .lowered due to .thelescent of the` said pawl 5, whose' lateral pin 11 movesinto engagement with the edge ofthe' trip lever 13, which it slightly depresses.V l

:Thel piti V11 continues to Y move parallel to the rack whilethe pa'wl 5 is under load, until the inner pawl` 6, which, during this movement, has been raised,l ista'ken byy its spring into engagement with a .tooth of t-hev rack, and supports the load, when the spring 17 acts .sol as to' throw the upper pawl 5 v'com-pletely out of engagement, as 'in Fig; 5.

The' load being now taken Vby' the inner pawl, theoperating lever is raised, causingthe-sai'rlpawlto be lowered and to engage with trip. lever 1-4 and 'compress its spring, which. actstothirow the' saidy pawl out of engagement with the rack.. immediately the upper pawl 5 'moves into engagement and.

takes .the load, as in Fig; 4;

Instead ofthe trip' Vmembers consisting of r ii-veted`` arms lacted upon by springs, they I Amay consist of pla-1n wire springs or of leaf springs carryingV bosses orVv raised parts at the ends; i i

'In the case of asshown inFig-, 6, having a retaining pawl 24ufoi' holding the load 'while the lifting pawl 6 is withdrawina trip lever 14 (shown as a pivoted leaf springlis employed in connection .with said' lifting pawl. Between .fthe latter v andthe retainingV pawl 24, however, a doublesarmed leaf. or wire spring 25 is employed Vmounted upon the rocker 15l which "carries/.the lower. trip. lever 14, 'lf' the detent 21 is depressedso as to more the rotzlieigliintothe` lowering pcsitilon, thenas'the lifting' "pawl (iis raised. to engagelthe rack 7, .its lateral .pin'12 engages vthe lower army ofsaid double-armed spring, moving the. upper-` arin into" engagement ivi-tiri a lateral-i pin .111on the.. retaining pa'wl.- The arms of the spr-ing areithus pressed together until the pressureupon" the pin 11 isv snflil cient to throw the retaining pawl out` of.

engagement. The load is then lowered by "the, pawll 6, Vuntil the latter. isthrown out rocker 15,wliich is pivoted at 16 andl heldv in` eitherof two positions vbythedetent 21, asv

ofl engagement by the trip` lever "14, prior to which the retainingpawl 24 will have rengagedi tliepracli dueto the pressure of the spring 25. being relieved due. to the de-V Y .scentof the. lifting-pawl.

l-n-the modification .represented in which shows a double-.acting jack, the trip.

members 13, 14, consistofv arms rigidly cai'- ried upon a lever 26` pivoted at 27 to the in Figs. 1 to 5l The arms ortrip members a single-acting jack, such- 13, 14, are influenced by the spring 28 pressingupon the studi291 of the lower arm 14. The studs 11, 12, on the pawls 5, 6,

-, engagevwith the trip arms 13, 14, as in the locl'ing the. rocker in' an operative position for lowering, in4 which the tripmembers tairel a position such that they act upon the pawls, as the latter are lowered, so vas to throw said'pawls out of engagement.

2. fr lifting jackv comprising a ratchet-v toothedraclt', an cperating lever, pawls car'- riedby the' lever,- a rocker carrying springact-uated, trip levers lpivote'd thereon, stops on the 4 rockeragainst whichjthe `trip levers are maintained, means for locking the rocker in aninoperative position where the trip levers have no eiiect. upon Vthe pawls, land f meansY for ioeki-'ng-the i'ockeizin an opera# tive position foi-'lowering so' that-the trip levers are engagedy byythe .pawls,." as the latter descend, and Vcause said pawlsv tof be throw-nv out of engagement with the rack.

3. doi'ihle-acting .lifting v"jack Ycempris.-A

ing a lratchet'-to'e'tli ed rack, operating lever, twe lifting pafwlsA carried by they lever and `coperiatiilg with therack, a rocker earring two Vspr-ing-actuated trnifleveis piveted' tlfifefr'e'on; foi" eop'erating with the re- Y spc'tiyepawlsg mea-nsfer locl'rring therccker inaiif inoperative 1positien .where the tripV leversehave 1 i"ei ef'eet upon the parvis, an#V means'for locking the rocker in; an operative position for; 10W-einig, the'. 'one pievi," as a descencls-beingmei'eel out of engagement by its-'trip .in'eififi'beri` while thev other pawl, A in rising', moves iiiteengagement with the rack..

said- -disengag'ed --pawl venga.ging with' Y another tooth when again lifted.

4. A lifting jack comprising pawl .and ratchet lliftingV mechanism, Vanl operating lever,` a rocker carrying relativelyv angularlymovable spring actuated trip members adapte-dito eo-perateI with thevlifting pawls, anda( pivoted locking -lever cooperating with a projection onthe rocker in order .teloeli the flatterin a position 'for lowering'the load, v In testimony whereof I have hereunto set my hand in presence of a subscribing wit- 

